J-2X powerpack completes 2012 testing ahead of SLS role

December 14, 2012 by Chris Bergin

The powerpack assembly for the Pratt & Whitney Rocketdyne (PWR) J-2X engine has completed its year of testing at NASA’s Stennis Space Center in Mississippi. The engine is set to provide the Earth Departure Stage (EDS) role for astronauts and hardware heading to destinations in deep space, should NASA opt to evolve SLS to the Block II configuration.

J-2X and SLS:

The new Heavy Lift Launch Vehicle (HLV) is currently set to evolve through three major configurations, opening with a 70mt Block 1 design, providing the vehicle for what is presently two test missions to send Orion on an uncrewed – then crewed – flight around the Moon.

With political requirements in the 2010 Authorization Act – created under the guidance of NASA managers – stating the need to provide a 130mt capable vehicle that utilized former Shuttle and CxP hardware, the J-2X was handed a lifeline, but only with the Block II SLS. As such, three J-2X engines are baselined into the Earth Departure Stage (EDS) on the fully evolved SLS.

Moving past the ongoing arguments about the need for a Block II SLS, the J-2X – the first human-rated liquid oxygen and liquid hydrogen engine developed in the United States in decades – will be a very capable engine.

This latest variant is capable of generating 294,000 lbf (1,310 kN) of thrust, and is being tested at the new A2 test stand at Stennis Space Center. Testing began with P&W Rocketdyne successfully evaluating the initial J-2X gas generator design in 2008, followed by the completion of a second round of successful gas generator tests in 2010.

This week marked the final test-firing of the J-2X powerpack assembly for 2012, a system of components on top of the engine that feeds propellants to the bell nozzle of the engine to produce thrust.

There are currently three major elements of J-2X hardware at Stennis, the 10001 engine, the powerpack and the 10002 engine – the latter of which was last noted as undergoing engine valve installation inside Stennis building 9101.

Showing the importance of testing, the hardware has provided few minor tantrums throughout the year, examples of which the early shutdown on a test in late September.

“The J-2X engine 10001 has completed its test series in the SSC A-2 test stand, completing 21 tests and 2,717 seconds hot fire time. Test #21 on September 25, 2012 was cut off at 3.5 seconds of the planned 250 second test, due to low discharge pressure at the fuel turbopump,” according to notes provided to L2’s J-2X Update Section.

“The engine was shut down safely. Post-test data review and hardware inspections found the engine experienced a combustion “pop” (anomalous lox/fuel detonation) inside the turbine drive hot gas system. The test failure team has determined root cause to be incorrect installation of the gas generator pyrotechnic igniters, resulting in failure to properly ignite the gas generator.”

The reason the powerpack was separated from the engine for evaluations is to allow for it to be more thoroughly tested to its limits. It also can be operated under a wider range of conditions, the results of which will tests provide a analytical predictions of the performance of several parts in the turbopump and flexible ducts.

The powerpack assembly burned millions of pounds of propellants during a series of 13 tests totalling more than an hour and a half in 2012. The testing team set several records for hot-firing duration at Stennis test stands during the summer.

“These tests at Stennis are similar to doctor-ordered treadmill tests for a person’s heart,” said Tom Byrd, J-2X engine lead in the SLS Liquid Engines Office at Marshall in Huntsville, Alabama. “The engineers who designed and analyze the turbopumps inside the powerpack are like our doctors, using sensors installed in the assembly to monitor the run over a wide range of stressful conditions.

“We ran the assembly tests this year for far longer than the engine will run during a mission to space, and acquired a lot of valuable information that will help us improve the development of the J-2X engine.”

NASA engineers will remove the powerpack assembly from the test stand to focus on tests of the fully integrated engine – likely to be engine 10002 – to undergo testing in 2013.

(Images: Via L2 and NASA)

(NSF and L2 are providing full exploration roadmap level coverage, available no where else on the internet, from Orion and SLS to ISS, Commercial, European and Russian vehicles.)